A significant relationship exists between the frequency of occurrence of certain types of sports player injuries and the quality of a playing surface. It is generally accepted that playing surface quality is primarily a function of turfgrass density and growth. A dense growth of turfgrass is thought to provide a cushioning effect that improves players' safety. The soil or other growing medium on which turfgrass is grown is not generally considered a significant factor, per se, in achieving this cushioning effect, although it is well recognized that increased soil moisture softens the soil in addition to enhancing turfgrass growth. Excess moisture, however, can cause reduced traction and, if severe, poor root growth and loss of stand density (number of plants per unit area).
The ultimate turfgrass sod for use on athletic fields and other areas where heavy wear stress is anticipated would include, as a minimum, the following characteristics: (1) a minimum water infiltration rate of 8 to 10 inches per hour, (2) high resiliency, (3) a minimum available water holding capacity of 10 weight % (based on sod dry weight), (4) a source of slow-release plant nutrients, (5) a dense root matrix for sod integrity and resistance to divot removal and/or sod tearing and (6) a dense growth of well adapted turfgrass species. Many of these sod characteristics would also be useful for other types of plants such as flowers.